IN-DEPTH: HIND LEG FROM THE PELVIS DOWN


evolve into a case with pre-conceived ideas regard- ing diagnosis. Age, breed, discipline, training, com- petition history, plus previous lameness history, treatment, and diagnostics are all important. Al- ways make sure the horse being examined is not presently on any drug that would be an analgesic affecting the examination. Always examine the foot first to rule out the very


basic hoof abscess. As evolved as veterinary medi- cine has become in lameness diagnostics, realize that these are quite common. This can segue into a discussion of hoof testers. They are not a highly advanced tool, but it is worth noting they can be used to discern between two types of pain: epicritic and protopathic. Epicritic fibers are A-fibers that are myelinated, large diameter, and fast conducting, transmitting sharp localized pain.1 For example, the immediate pain obtained around the periphery of the foot with hoof testers with an abscess or bruise. Protopathic fibers are C-fibers that are un- myelinated, small diameter, and slow conducting, transmitting poorly localized, dull, aching pain.2 For example, the type of pain elicited with sustained pressure of hoof testers across the heels with “heel pain” syndrome. Step back to get a visual examination of the pa-


tient–conformational abnormalities, muscling, pos- ture, body score, and any evidence of metabolic issues. A thorough assessment of body symmetry is essential, this is a history book of how the horse has been using and abusing its body. Make sure the patient has a square stance on level ground. Kneel down in front of the horse and look up to gauge neck structure and muscle symmetry. Standing in front of the horse, lower the head to evaluate cranial, poll, and neck symmetry from above. From behind, evaluate pelvic symmetry, hind-end muscle symmetry, back and shoulder sym- metry. Pelvic asymmetry should be judged care- fully–are the bony protuberances bilaterally similar (height, width, and contour)? For instance, if the tuber sacrale are different heights, there are three main causes: a true pelvic traumatic shift, enlarge- ment of one dorsal sacral ligament (funicular por- tion), or a chronic lameness on the opposite side of the higher tuber sacrale (biomechanically, the sound side will be driven higher over time). Asymmetric structure causes asymmetric function and asymmet- ric function over time will create its own repetitive trauma. Kneel down again, to evaluate feet for symmetry and condition. The author’s approach from here is to palpate, manipulate, and perform mobility testing of the neck, back, pelvis, and all four limbs (only hindlimbs for this presentation). In the author’s opinion, per- forming the same exam every time, will reduce the likelihood of missing valuable clinical information. The axial skeleton can directly affect hind-end movement, so it is ideal to start here. The neck and associated abnormalities can certainly play into ab- normal hind-end movement, including a range of


neurologic dysfunction, which when subtle, can be dif- ficult to distinguish from lameness. Careful static palpation and palpation during movement are impor- tant. The author prefers baited carrot tests to assess cranial, mid range, and caudal lateral mobility bilat- erally, as well as flexion and extension. Then move to the back, palpating the dorsal midline and epaxial muscles bilaterally, observing for sensitivity, fascicu- lations, and textural differences. Mobilization of the back (flexion, extension, and lateromotion) are invalu- able. Completing axial skeletal evaluation, perform careful palpation and mobilization (flexion and exten- sion) of the pelvic region. Stallions should have tes- ticles palpated and geldings should have castration sites palpated. These are not common sources, but abnormalities can be associated with hind-end lame- ness. It is also possible for ovarian pain in mares to be related to abnormal hind-end movement. Proxi- mal limb structures and muscles should be palpated carefully for sensitivities and abnormalities in tex- ture. Classic fibrotic myopathy is well known; what is not well known is subclinical or mild clinical fibrotic myopathy. Significant pressure should be used when palpating the region of the greater and third trochanters. Continuing down the limb, the stifle should al-


ways be palpated in a squared, full-weight-bearing position first. Start with collateral and patellar lig- aments and their associated bony insertions. Joint recesses should be palpated for both fluid disten- tion and joint capsule quality. The stifle should also be palpated as the limb is rocked in and out of the locked position, as a test for upward fixation of the patella. Apply caudal pressure to the anterior aspect of the patella. This is a good test for femo- ropatellar joint inflammation. Don’t forget the gaskin or crus region, palpating bone surfaces, mus- cles, and especially the calcanean tendon region. Continuing distally to the tarsus, carefully palpate


joint surfaces, joint capsules, tarsal tendon sheath, all associated tendons and ligaments, and plantar meta- tarsal fascia. Palpate metatarsal bones, and plantar metatarsal soft tissues. Note any metacarpophalan- geal joint and digital tendon sheath distension and capsule quality. Are there any interference marks? Palpate proximal and distal interphalangeal joint sur- faces, recesses and capsules, collateral ligaments of all distal joints and the plantar pastern soft tissues. Are there significant digital pulses or heat in feet? The feet should be evaluated in both weight bearing and in hand, paying attention to shape, angles, toes/ heel length, symmetry, breakover, horn quality, coro- nary band sensitivity/texture, flexibility of collateral cartilages, alignment with limb, and if wearing shoes, shoe-wear distribution patterns. Continue with unweighted palpation. Is the pa-


tient willing to pick up the limb and are they com- fortable holding it flexed and extended? Do the joints have normal range of motion and is there any pain during this manipulation? When holding up a limb, evaluate the metacarpophalangeal joint


AAEP PROCEEDINGS  Vol. 65  2019 333


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